Simple filament jam and runout sensor
Description
I have seen a lot of different ways to detect filament jams, and they all require additional sensors and several extra parts, hardware, electronics, etc. Or they only detect if the filament gets caught on the sensor itself. So I wanted to make a version that used a regular microswitch found in the cheap filament sensors from china, like this one https://www.aliexpress.com/item/32967361574.html?spm=a2g0o.productlist.0.0.49cb3e9bkaVVTk&algo_pvid=f2f160e5-7fcb-4902-be8b-a30954faae5f&algo_exp_id=f2f160e5-7fcb-4902-be8b-a30954faae5f-0 and didn't use any hardware (besides a few pieces of ptfe tube) I got the idea to detect filament tension from this thing: https://www.thingiverse.com/thing:4299458 All you need to do is: 1. Print the screw and base. I used 2 perimeters but it doesn't matter much. If you want to have this on the hotend moving around, lighter will be better. PLA and PETG will both work fine. 2. Disassemble the original sensor, and push the little microswitch board into place as shown with the switch downwards. If it is a little loose, you can hot glue it or something. I'm not sure how consistent the size of these boards are, just FYI! It may not fit all switch boards. I'm counting on the community to remix this thing and make it work better :). 3. Clear out the holes for the PTFE tubes using a razor blade or tiny screwdriver. 4. Push a piece of ptfe tube into one of the holes until it goes all the way down, then cut it off with flush cutters. Repeat for the other hole. This will create a nice low friction channel for the filament to go through. 5. Install the screw into the base. Tightening this screw will make it harder for the sensor to trigger. Loosening it will make it easier. 6. Plug the sensor in, and insert filament. I recommend having the sensor stationary, just by zip tying it to the frame or something. This reduces the weight on the hotend, and allows you to reduce the bend radius, which reduces the friction added by the sensor. This will reduce the likelihood that you falsely trigger the sensor. To tune the sensor (so it triggers at the right time), you can run the filament through the extruder while holding onto the filament to create tension. The switch should trigger right before the extruder starts to lose steps. You can use the screw to adjust it to be perfect. Then if you want to lock it in place, put a drop of super glue or loctite on the screw so it can't vibrate loose. How it works: When the filament is under tension, it will pull on the arm. The arm will flex, pulling the switch away from the filament and allowing the switch to open. By adjusting the screw, you are effectively making it harder for the arm to flex, so you change when the switch opens. Of course it also works as a filament runout sensor. When the filament is not present, the switch will open. How to remix it: Either you can use tinkercad, and import the stl files, or you can use Onshape and make a copy of my file here: https://cad.onshape.com/documents/212d638df7abe6ae676082a9/w/0b38859e31c616f3202aaf06/e/9ea9fb956f8a4bfa5910f1f4
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